I sometimes get an exception when clicking on the plot.

Short description

Code to reproduce

clinking on the plot sometimes causes the issue

Expected behavior

no error

Real behavior

An exception is raised because self.clickEvents is an empty list at that time.

File "D:\TMP\daxil_venv_3.9\lib\site-packages\pyqtgraph\GraphicsScene\GraphicsScene.py", line 243, in mouseReleaseEvent
    self.clickEvents.remove(cev[0])

Tested environment(s)

• PyQtGraph version: 0.12.3
• Qt Python binding: PyQt5 5.15.6
• Python version: 3.9.4 x64
• NumPy version: 1.21.2
• Operating system: Windows 10 x64
• Installation method: pip

Additional context